Embodiments of the present invention are directed toward wideband cavity-backed slot antennas.
There is a need for conformal ultra wideband antennas for applications such as data links and electronic surveillance measures (ESM). These and other applications require moderate gain (˜0 dBi) across a wide frequency band. Some applications require horizontally polarized signals in order to optimize system performance. It is also desirable to reduce or minimize the size, weight, and power consumption (SWAP) of the antenna.
In the field of microwave antennas, cavity-backed slot antennas are well known in the art. One advantage of slot antennas over dipole antennas is their relatively small size. For example, a cavity-backed slot antenna may be less than 1″ thick and an array of such antennas can be mounted on or formed as part of the outer wall of a building or on an outer surface of a vehicle, whereas a dipole antenna typically must protrude from these outer surfaces. However, cavity-backed slot antennas typically provide only up to approximately 3:1 bandwidth ratio (i.e., the ratio of the maximum frequency to the minimum frequency) and in some applications, it is desirable to have a cavity-backed slot antenna with a bandwidth ratio larger than 3:1.